Post singulation die separation apparatus and method for bulk feeding operation

ABSTRACT

A post singulation, die separation assembly for bulk separation of a plurality of dice in a singulated wafer from the adhesive backing of wafer saw tape. The die separation assembly includes a support base having a support surface, a first portion and an opposite second portion thereof. The second portion includes a down-ramped portion thereof skewed downwardly at a first acute angle from the support surface. A feed tray includes a collection end positioned adjacent the base second portion such that an elongated, substantially thin gap is formed between the tray collection end and at least a portion of the base second portion. A flexible platform is movably supported atop the base support surface for movement from the first portion to the second portion thereof. At the second portion, the platform passes downward through the gap formed between the tray collection end and the at least a portion of the base second portion. The platform defines an upward facing surface upon each die of the singulated wafer is adhered thereto, via the saw tape, in a forward aligned manner. Upon movement of the flexible platform down the down-ramped portion of the support base, a portion of the wafer saw tape thereat is peeled away from the respective die. The tape is the separated from the dice, releasing the respective dice onto the collection end of the feed tray in a manner substantially maintaining their forward alignment orientation of thereof.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to post die singulation ofwafers, and more particularly, relates to separation of dice from wafersaw tape while substantially retaining the orientation die duringseparation.

2. Description of the Related Art

Semiconductor Integrated Circuits (ICs) are typically fabricated inwafer form on wafer saw tape. After fabrication, using precision cuttingtechniques, individual die are cut or singulated from the wafer withoutcutting through the saw tape. In the past, where the precise orientationof the die was necessary, a tape and reel assembly was typically appliedto transport the chips to the individual processing stations. The tapeand reel assembly includes a tape with a plurality of transport cavitiesspaced at regular intervals. Once a chip has been placed inside atransport cavity, the cavity is sealed with an adhesive tape so the chipcan be safely transported from station to station by the tape and reelassembly. However, to transfer chips singulated from a wafer into thecavities of the tape and reel assembly, special devices, known as devicetransfer machines were used.

As shown in FIG. 1, these special transfer machines 15 are responsiblefor transferring and flipping a semiconductor device, such as a flipchip die 16, from a singulated wafer to a transport cavity 17 which ispart of the tape and reel assembly 18. The transfer to the transportcavity 17 is complicated by the small size, delicacy and orientation ofthe die 16. An exemplary flip chip die may be about 35 mils square,which limits the applicable handling techniques. In addition, aftersingulation, the die is precisely oriented with its solder bumps facingup. However, in order to mount the die, it has to be placed in thetransport cavity with the solder bumps facing downward.

Typically, the transfer machine 15 includes a robotic loading arm oranother suitable pick and place mechanism 19 that precisely picks andplaces the die 16 from the wafer saw tape 20. The loading arm 19 usuallyincludes a head housing a vacuum tube that applies a vacuum pressure onthe support surface of the die between the solder bumps to transport thedie from the saw tape 20 to the transport cavity 17. To dislodge the diefrom the adhesive of the wafer saw tape 20, however, the vacuum tubeapproach alone is usually insufficient.

One technique and apparatus applied to separate the adhered die from thesaw tape 20 is to apply a needle push-up system 21 with vacuumassistance to facilitate retention of the wafer saw tape during thepush-up procedure. As shown in FIG. 2, when a selected die 16 isproperly positioned over the push-up system 21, a push-up needle 22thereof moves the die 16 upwardly and partially separates the die fromthe wafer saw tape 20 from underneath. When the push-up needle 22 beginspushing the single die 16 upward from below, the vacuum assistancecommences to retain the saw tape 20 surrounding the die against thesupport surface 25. The saw tape 20 is then peeled off the die backside,releasing the adhered die. Subsequently, a robotic loading arm 19 picksthe die and places it in the transport cavity.

Before placement of the die 16 in the transport cavity 17, however, theloading arm 19 must flip the die 16 over for proper positioning in thetransport cavity 17. The transfer machine 15, thus, typically includes aflipper mechanism 26 that works in conjunction with the loading arm. Inthe past, the loading arm 19 picked the separated die 16 and placed iton a platform of the flipper mechanism 26, which then rotatably flippedthe die over. Once flipped, as simplified in the following description,the platform would release the flipped die into the transport cavity forfuture chip processing. More recently, the loading arm places theseparated die into a station of a multi-station rotary die handlingdevice which significantly improved the flipping capacity. This designis the subject of U.S. Pat. No. 6,364,089 which is incorporated byreference in its entirety.

While these current device transfer machines adequately perform theirrespective functions, they are problematic for a number of reasons. Forexample, the needle push-up technique applied to remove the die adheredto the wafer saw tape is slow, tedious and complex. Depending upon theheight and weight of the dice, certain parameters require properadjustment such as pick and bond forces, height adjustment, etc. Due tosuch complex physical demands and restraints, a bulk removal approach ofthe dice from the wafer saw tape cannot be accommodated. This representsa significant bottleneck in the overall IC testing and packagingsequence.

In view of the foregoing, a device transfer machine with improvedthroughput would be desirable.

SUMMARY OF THE INVENTION

The present invention is directed to a post singulation, die separationassembly configured for bulk separation of a plurality of dice in asingulated wafer from the adhesive backing of wafer saw tape. The dieseparation assembly includes a support base defining a support surfacehaving a first portion and an opposite second portion thereof. Thesecond portion include a down-ramped portion skewed downwardly at afirst acute angle from the support surface. The separation assemblyfurther includes a feed tray having a collection end positioned adjacentthe base second portion such that an elongated, substantially thin gapis formed between the tray collection end and at least a portion of thebase second portion. A flexible platform is movably supported atop thebase support surface for movement from the first portion to the secondportion thereof. At the second portion, the platform passes downwardthrough the gap formed between the tray collection end and the at leasta portion of the base second portion. The platform further defines anupward facing surface upon which of the singulated wafer is adheredthereto, via the saw tape. The wafer is to be positioned such that eachdie is in a forward aligned manner. Upon movement of the flexibleplatform down the down-ramped portion of the support base, a portion ofthe wafer saw tape thereat is peeled away from the respective die. Atthis region, the portion of the tape is separated from the dice,releasing the respective dice onto the collection end of the feed trayin a manner substantially maintaining the forward alignment orientationthereof.

Accordingly, unlike current die transfer machine designs, the presentinvention enables bulk removal of multiple dice of the same singulatedwafer from the adhesive wafer saw tape. At the same time, the forwardalignment orientation of each separated die is maintained which enablesbulk feeding to subsequently die handling devices that substantiallyincreases manufacturing capacity.

In one specific embodiment, the base second portion further includes anup-ramp portion of the base skewed upwardly at a second acute angle fromthe support surface portion, oriented just before the down-ramp portion.The up-ramp portion and the down-ramp portion intersect an apex edgeportion. It is at this edge portion where the saw tape is peeled awayfrom the respective die during movement of the adhered wafer along thebase. When no up-ramp portion is provided, the first acute angle of thedown-ramp portion (from the support surface) is in the range of about60° to about 90°. When an up-ramp portion is applied, as set forthabove, the first acute angle is in the range of about 45° to about 60°,while the second acute angle (between the support surface and thedown-ramp portion, is preferably in the range of about 15° to about 30°.This forms an intersection angle at the apex edge portion in the rangeof about 90° to about 120°.

In another embodiment, the collection end of the feed tray includes acollection surface disposed at an elevation proximate to that of theapex edge portion. Further, the thin gap formed between the traycollection end and the down-ramped portion is less than the height ofthe separated die. However, the gap height is also more than thecombined thickness of the flexible platform and the adhered saw tape.This facilitates aligned transfer of the separated dice onto thecollection end of the feed tray, while preventing lodging of the dice inthe gap.

A top plate device is included in another embodiment that is positionedproximate to the base second portion, and vertically spaced-apart fromthe base support surface. During peeling of the saw tape from the diceas they pass over the apex edge portion, the top plate devicesubstantially prevents flipping of the respective die by pushing down onthe upper surface thereof, while at the same time maintaining the die'sforward alignment orientation.

In still another specific embodiment, a driven roller assembly isincluded having a first roller and a second roller. The flexibleplatform is in the form of an elongated sheet material having one endwound around the first roller, and the opposite end wound around thesecond roller. Preferably, the elongated sheet material is provided by aone-sided tape material.

In yet another aspect of the present invention, a post singulation, bulkfeed semiconductor assembly is adapted to separate the adhesive wafersaw tape from the plurality of dice of a singulated wafer, wherein thesame is bulk feed in a substantially aligned manner. The assemblyincludes a semiconductor feed tray having a collection end and anopposite feed end. A collection surface of the feed tray extends fromthe collection end to the feed end. A die separation assembly includes asupport base defining a support surface and having a first portion andan opposite second portion thereof. The second portion is positionedsubstantially adjacent the collection end of the feed tray such that thebase support surface is positioned elevationally proximate the traycollection surface. This forms a thin elongated gap between the traycollection end and the base second portion. A movable platform ismovably supported atop the base support surface for movement from thefirst portion to the second portion thereof. At the second portion, theplatform is directed downward through the elongated gap formed betweenthe tray collection end and the base second portion. The downward rampis skewed at a first acute angle from the support surface. The platformdefines an upward facing adherence surface upon which at least one of aplurality of singulated wafer is adhered thereto, via the saw tape. Eachdie is substantially maintained in a forward aligned manner, whereinupon movement of the platform through the thin elongated gap, a portionof the wafer saw tape thereat is peeled away from the respective die ordice. This separates and releases the respective die or dice onto thecollection end of the feed tray in a manner substantially maintainingtheir respective forward alignment orientation. As the dice aretransferred onto the feed tray, the subsequent dice urge the currentlydeposited dice toward the tray feed end and into contact with therespective dice previously released onto the collection surface.Finally, the bulk feed semiconductor assembly includes a die alignmentassembly oriented at the feed end of the feed tray, and adapted tocollective cooperate with the dice at the tray feed end for finalalignment before removal from the feed tray.

In one specific configuration, the feed tray includes a plurality ofseparation walls upstanding from the collection surface and extendinglongitudinally from proximate the collection end to proximate the feedend of the feed tray. In another arrangement, a die timing and alignmentassembly is included having a die alignment stopper extending across andtransverse to the feed tray. The die alignment stopper is selectivelymovable between a first position, preventing passage of the dice at thefeed end therethrough, and a second position, permitting passage of thedice therethrough.

In another embodiment, a semiconductor handling device is included thatis positioned proximate the feed end of the feed tray. This handlingdevice enables bulk feed of the aligned dice into discrete stations ofthe handling device for subsequent die placement thereof.

The die timing and alignment assembly further includes a die mountingstopper extending across the discrete stations of the handling device.This second die stop is selectively movable between a load position,enabling loading of the dice onto the handling device at the discretestation, and a transport position, permitting transport of the loadeddice on the handling device.

BRIEF DESCRIPTION OF THE DRAWINGS

The assembly of the present invention has other objects and features ofadvantage which will be more readily apparent from the followingdescription of the Detailed Description of the Embodiments and theappended claims, when taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a side elevation view of a prior art die transfer machine,including a die pick and place mechanism and a die flipping mechanism.

FIG. 2 is an enlarged side elevation view of a prior art die push-upsystem.

FIG. 3 is a top perspective view of a post-singulation die separationapparatus constructed in accordance with the present invention.

FIGS. 4A–4C is a sequence of enlarged, fragmentary, side elevationviews, in cross-section, of the die separation apparatus of FIG. 3, andillustrating removal of the wafer saw tape from the singulated wafer andloading onto a die transfer mechanism.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While the present invention will be described with reference to a fewspecific embodiments, the description is illustrative of the inventionand is not to be construed as limiting the invention. Variousmodifications to the present invention can be made to the preferredembodiments by those skilled in the art without departing from the truespirit and scope of the invention as defined by the appended claims. Itwill be noted here that for a better understanding, like components aredesignated by like reference numerals throughout the various figures.

Attention is now directed to FIGS. 3 and 4, where a post singulation,die separation assembly, generally designated 30, is illustrated forbulk separation of a plurality of dice 16 of a post singulated waferassembly 31 from the adhesive wafer saw tape 20. The die separationassembly 30 includes an elongated support base 32 having a supportsurface extending from a first portion 33, on one side of the base, to asecond portion 35, on an opposite side thereof. As best viewed in FIG.3, the base second portion 35 includes a down-ramped portion 36 thereofthat is skewed downwardly at a first acute angle from the generallyhorizontal support surface 37. A feed tray, generally designated 38,includes a collection end 40 positioned adjacent the base second portion35 such that an elongated, substantially thin gap 41 (FIGS. 4A–4C) isformed between the tray collection end 40 and at least a portion of thebase second portion 35. A flexible platform, generally designated 42, ismovably supported atop the base support surface for movement from thefirst portion 33 to the second portion 35 thereof.

FIG. 4A best illustrates that at the second portion 35 of the supportbase 32, the flexible platform 42 passes downward through the thin gap41 formed between the tray collection end 40 and the at least a portionof the base second portion 35. In accordance with the present invention,by adhering the backside of the wafer saw tape 20 to the upward facingsurface of the flexible platform 42 in an aligned manner, the saw tapewill be peeled from the dice 16 proximate the location where theflexible platform passes through the gap.

Accordingly, upon movement of the flexible platform 42, with the adheredwafer saw tape 20 thereto, down the down-ramped portion 36 of the basesecond portion 35, a portion of the wafer saw tape 20 thereat is peeledaway from the respective die or dice 16. As viewed in FIG. 3, the sawtape 20 is separated from the dice (nearly simultaneously depending uponwhich row), releasing the respective dice 16 onto the collection end 40of the feed tray 38. In accordance with the present invention, once thesaw tape 20 is peeled from the respective row of dice 16, they aredelivered atop the collection end 40 of the feed tray 38 in a mannersubstantially maintaining the forward alignment orientation that eachdie held before separations. Briefly, it will be appreciated that aforward aligned orientation is defined essentially as any predeterminedand desired alignment of the die.

In contrast to the transfer machine designs where the pick and placemechanisms only remove a single die at a time, the present inventionenables bulk removal of the dice from the same singulated wafer.Consequently, as viewed in FIG. 3, the separated dice can also be bulkfed to a subsequent die handling device that can handle the increasedcapacity, thereby eliminating any intermediary “pick and place” device.Manufacturing capacity is thus significantly increased, as well assubstantially simplifying the operations.

Referring back to FIGS. 4A–4C, it is shown that the support surface 37of the support base 32 is preferably planar and horizontal. Further, inone specific configuration, the support base 32 is relatively rigid forsupport of the flexible platform 42 and mounted wafer assembly 31thereatop. The base support surface 37 is also preferably substantiallysmooth and absent of any sharp edges or corners so as to promoteunobstructed sliding of the bottom side of the flexible platform acrossthe base from the first portion 33 to the second portion 35 thereof.Accordingly, as will be discussed, the base second portion 35 includesan apex edge portion 43 that is sufficiently angular to promote peelingof the saw tape 20 from the dice 16 as the flexible platform passesover, but at the same time edge portion must not be too sharp to impedepassage of or cause severing of the flexible platform.

In other embodiments, however, the support surface 37 of the supportbase 32 can be semi-rigid. It will be appreciated, however, that thesupport surface should be sufficiently rigid such that peeling will beenabled at the respective portion of the saw tape when the respectivedice pass over the apex edge portion 43. It will further be appreciatedthat other support structures may be incorporated to promote movementalong the support surface 37, such as, for instance, rolling supportthrough the addition of roller devices or the like.

In the preferred form, the flexible platform 42 is of a sufficient widthto accommodate the entire singulated wafer and the wafer saw tape 20upon which is mounted (i.e., the singulated wafer assembly 31). As bestshown in FIG. 3, once the wafer ring (not shown) is removed, theperimeter of the saw tape often extends beyond the perimeter of theremaining singulated wafer. Prior to peeling of the wafer tape 20 fromthe sawn dice 16, the singulated wafer assembly 31 is placed upon theflexible platform 42 between the base first portion 33 and the basesecond portion 35. Such placement may be automated or performedmanually, but must be positioned in a manner where the dice are in thedesignated forward alignment orientation.

To adhere the wafer saw tape 20 to the flexible platform 42, either thebottom surface of the saw tape or the support surface 37 of the flexibleplatform may include an adhesive to promote adherence therebetween. Mostimportantly, it is imperative that the outer perimeter portion of thesaw tape 20 be adhered to the flexible platform, especially the initialor very front tape portion 46 of the outer perimeter portion, so thatwhen the corresponding portion of the flexible platform 42 and theadhered saw tape 20 moves into the thin gap 41, that very front portion46 of the saw tape is drawn therein rather than itself separating fromthe flexible platform. Should such initial separation of the saw tapeoccur from the flexible platform, the entire singulated wafer assembly31 would then be delivered atop the collection end of the feed tray. Toassure initial tape separation into the thin gap 41, in some instances,an additional adhesive tape 47 may be provided over the front tapeportion 46 of the outer perimeter. As shown in FIG. 3, this effectivelysandwiches the front tape portion 46 between the additional adhesivetape 47 and the flexible platform to promote the initial peeling at theapex edge portion 43.

Preferably, the flexible platform 42 will contain the applied adhesiveto the upper surface thereof. In one specific embodiment, the flexibleplatform is provided by a roll form of one-sided adhesive tape.Moreover, as best shown in FIG. 3, to enable a continuous feed of theflexible platform 42 (e.g., the one-sided tape) across the support base32, a roller assembly 48 is incorporated into the system. The rollerassembly 48 includes front roller 50, positioned proximate the basefirst portion 33, and a rear roller 51, positioned proximate the basesecond portion 35. Working in tandem, the front roller 50 supplies theflexible platform 42 to the support base 32, while the rear roller 51functions to collect and roll the utilized flexible platform and adheredsaw tape 20 from atop the support base 32.

At least one of the rollers is conventionally driven to move theflexible platform from the first portion of the base to the secondportion thereof. Movement of the flexible platform 42 across the supportbase can be selectable controlled, depending upon the desired rate ofdelivery of the dice to the feed tray. This speed, however, will berelatively slow, although depending upon the size of the dice, thisspeed may adjusted accordingly.

To assure continuous tension of the flexible platform 42 atop thesupport base 32, some form of tensioning device and/or tension sensorsare utilized that work in conjunction with the rollers. Such tensioningdevice, cooperating with the tension sensors, can be automated to assurethe proper degree of continuous tension across the support base. This isespecially important across the apex edge portion 43 where tape peelingoccurs. Such tensioning promotes proper peeling of the tape from thedice, as well as assures that the tape will not fold over the gap andonto the collection end 40 of the feed tray 38.

In accordance with the present invention and as mentioned above, peelingof the saw tape 20 from the singulated dice 16 occurs at the apex edgeportion 43 between the support surface 37 of the base and thedown-ramped portion 36 of the base second portion 35. Since the die ordice 16 are relatively rigid, and the saw tape is adhered to theflexible platform, as the wafer assembly passes over the apex edgeportion 43 (FIG. 4A), the portion of the tape at this intersection ispeeled back therefrom.

Accordingly, to promote tape peeling at the apex edge portion 43, thedown-ramped portion 36 must be at an angle sufficiently acute from thebase support surface 37 (e.g., a substantially horizontal surface). Thisangle has been determined to be at least in the range of about 60 deg toabout 90 deg. Moreover, while the apex edge portion 43 need not be adistinct edge, the radius of curvature of this edge must not be so largethat die merely rides over the apex edge portion without the front edgeportion of the die lifting up and separating from the saw tape 20.Accordingly, in one configuration, depending upon the size of the die,the radius of curvature may be in the range of about 10 mil to about 20mil. Otherwise, rather than ensuring that the front edge of the die willland atop the collection end 40 of the feed tray 38, it may initiallycommence movement down the gap 41 which would be problematic. Anotherrequirement, as already indicated, is that the tension of the flexibleplatform 42 be maintained as it travels over the apex edge portion 43.Insufficient tension, particularly at this intersection will impedeproper tape peeling.

Referring back to FIG. 3, in order to further promote peeling of thefront edge portion 43 of the saw tape 20 from the die or dice 16, thebase second portion 35 may further include an up-ramped portion 52 justupstream from the down-ramped portion 36 thereof. In this specificembodiment, it is this intersection between the up-ramped portion 52 andthe down-ramped portion 36 that defines the apex edge portion 43.Accordingly, as the dice 16 are urged up this gradual up-ramped portion52 by the moving flexible platform, once at the apex edge portion, theseparated dice continue travel in the direction of the upward slope(FIG. 4A). The flexible platform 42 and adhered tape 20, however,commence travel through the thin gap 41 and down the down-ramp portion,peeling the tape from the die or dice 16. Upon further advancement, thefront edge of the dice begin their descent, but over the collection end40 of the feed tray 38 (FIG. 4B). Once the front edge of the dicecontacts the upper surface of the collection end 40, the separateddie/dice are delivered onto the feed tray.

In this configuration, the slope of the up-ramped portion 52 is at anupward acute angle, from the substantially planar support surface 37 ofthe support base, in the range of at least about 15° to about 30°.Further, the down-ramped portion 36, in this configuration, is at adownward acute angle from the base support surface 37, in the range ofat least about 45° to about 60°. Collectively, the angular intersectionbetween the up-ramp portion and the down-ramp portion, at the apex edgeportion, is in the range of at least about 90° to about 120°. It is thusnoted that this acute angle is similar to that of the embodiment whereno up-ramp portion exists.

It will also be appreciated that the upper surface of the collection end40, in this configuration, is disposed at an elevation substantiallysimilar to that of the apex edge portion 43 of the support base 32. Thesimilarities in elevation promotes landing the separated die/dice atopthe collection end 40 during the separation cycle. It will beappreciated that the upper surface of the collection end 40 may beslightly above, and can be oriented slightly below the apex edge portion43 by a greater margin than can be oriented above the collection end,without departing from the true spirit and nature of the presentinvention.

Another important aspect of the present invention is the dimension ofthe thin gap 41 formed between the collection end 40 and the base secondportion 35 relative the height dimension of the dice. For example, thethickness or height dimension of the gap 41 must be sufficiently thin sothat the separated dice will not themselves pass through or becomesnagged passing over the gap 41. Thus, the gap thickness is preferablyat the very least less than the height of the dice being separated, andmore preferably at least ½ the height of the dice. On the lower end, thegap thickness is just greater than the combined thickness of theflexible platform 42 and the adhered saw tape thereto. More preferably,however, the gap thickness is in between these dimensions to assuresufficient tolerance for thickness variations and the like.

To maintain the gap thickness through the down-ramp of the base secondportion 35 accommodate the slope of the down-ramp portion, thecollection end 40 of the feed tray is also tapered to define a portionof the gap 41.

In accordance with the present invention, a dice top plate device 53 isemployed which substantially prevents flipping and/or substantiallymovement and rotation of the dice during separation from the saw tape atthe apex edge portion 43. Moreover, this top plate device 53 furtherfunctions to maintain the forward alignment orientation of each die whenit is delivered atop the collection end. This is especially importantupon final separation of the respective die 16 from the saw tape 20, atthe die rear corner thereof, which tends to lift the front end of thesame upwardly. Upon contact with a bottomside of the top plate device53, and with contact with the sides of adjacent dice, each die ismaintained in their forward alignment orientation.

As best illustrated in FIG. 4A, the top plate device 53 includes anelongated body portion 55 that is disposed transversely over the secondportion 35 of the support base 32. This is especially important at theregion where the individual dice 16 are separated from the singulatedwafer assembly 31 (i.e., above the apex edge portion 43). A distal edgeof the top plate device 53, hence, preferably terminates proximate theapex edge portion 43 of the support base 32. It will be appreciated,however, that the distal edge may terminate or be vertically disposedmuch further downstream at locations above the collection end 40 of thefeed tray 38 as well.

The elongated body portion 55 of the top plate device 53 extendssubstantially transversely across the entire width of the support base32, and as mentioned functions to prevent flipping of the dice 16 asthey are separated from the saw tape 20. Thus, the elongated bodyportion 55 is preferably substantially rigid (e.g., aluminum orstainless steel), and is cantilever mounted at an upstream end portionthereof. Thus, in some configurations, a downstream contacting portion56 is permitted to slightly reciprocate up and down due to contact withthe separated die 16. In other embodiments, the distance of contactingportion 56 of the substantially rigid plate from the apex edge portiondoes not vary significantly. It will be noted, however, that at no timeshould the bottom side of the top plate device 53 at the contacting endbe spaced-apart any greater than about twice the height of the die 16.

As each row of dice (typically) is delivered atop the collection end 40of the feed tray 38 during the die separation procedure, a respectivefrontside of each die will contact a backside of a respective die 16 inthe corresponding column directly in front of it (FIG. 4C). This contactaction during separation causes the corresponding column of dice to beurged forwardly longitudinally along the feed tray in the direction ofarrow 57. This procedure is the primary means to move and urge the diceforward towards a feed end 58 of the feed tray 38 for subsequenthandling of the separated dice.

In one specific embodiment, the columns of dice are maintained in theirsame respective columns as that of the singulated wafer. This approach,as shown in FIG. 3, is advantageous in that the length of the feed tray38 can be minimized or reduced versus other designs where the number ofcolumns along the feed tray 38 converge, as will be described. Byreducing or minimizing the length along the feed tray, the less thepushing force that is required to push the separated dice from thecollection end 40 to the feed end 58.

In this configuration, there may be provided a plurality of thin,longitudinally extending separation walls (not shown) positionedproximate the feed end that facilitate aligned separation of the diceatop the feed tray 38. These separation walls upstand from the uppersurface of the feed tray, and are oriented substantially parallel oneanother.

One problem with this approach, however, is that there will be a muchgreater density of dice delivered to the middle columns of the feed tray38 as opposed to that of the outside columns. As shown in FIG. 3, thisis a consequence of the circular shape of the singulated wafers. Thisdiscrepancy, however, must be accounted for when the dice are feed tothe subsequent die handling apparatus which will deliver significantlymore dice at the center of the feed tray than at the outer portionsthereof.

Accordingly, in another specific embodiment, the feed tray 38 may tapergradually inwardly from the collection end 40 to the feed end 58. Thenumber of delivery columns that are ultimately bulk fed to thesubsequent die handling device from the feed tray are thereby reduced.For example, a two-hundred column wafer can be narrowed or paired downto about twelve columns of dice at the feed end 58 of the feed tray 38.

Such gradual taper may be performed using the outer upstanding walls 60of the feed tray which would gradually taper inwardly, although notillustrated in FIG. 3. As the inwardly taped walls 60 converge, the dice16 also converge. In order to institute this design, it may be necessaryto lengthen the feed tray 38 to assure a gradual taper. Too much taperin too short a span may cause excessive interference between the dice asthey converge towards the feed end 58. Rather, this taper must besufficient to minimize the length the feed tray, while beingsufficiently gradual to eliminate clogging of the dice as they converge.

Moreover, as the dice are urged along the feed tray in the direction ofarrow 57 by the delivery of the separating dice, the dice must maintaintheir forward alignment orientation while converging at the same time.Any rotation thereof caused by position jostling during convergence willdefeat the purpose of the aligned delivery to the collection end. Theadvantage of this approach is that it significantly reduces the quantitydiscrepancy of the dice in the middle columns versus that of the outercolumns.

To facilitate die movement along collection tray from the collection end40 to the feed end 58 of the tray 38, in either the collection trayapproach, a high frequency vibration may be induced upon the collectiontray. Applying such high frequency vibration techniques, the lightweightsingulated dice are caused to simultaneously vibrate. Accordingly,smaller forces can be applied to the columns of dice to induce movementalong the tray. Moreover, in the tapered collection tray approach, thehigh frequency vibration unobstructed die merging of the convergingcolumns of dice while substantially maintaining the forward alignmentorientation thereof.

To further accommodate alignment of the dice 16 along the feed tray 38before delivery for subsequent die handling devices, an alignmentstopper, generally designated 61, may be incorporated. As best viewed inFIG. 4A, the alignment stopper 61 includes a rigid or semi-flexible flapportion 62 extending vertically downward toward the upper surface of thefeed tray 38. This flap portion 62 is preferably semi-flexible orsubstantially rigid in form.

The flap portion 62, which also extends transversely across the entirefeed tray 38, similar to the dice top plate device 53, is adapted forreciprocating movement between an alignment position (FIG. 4A) and apassage position (FIG. 4B). In the alignment position, the distal tip ofthe flap portion 62 is moved into contact, or near contact, with theupper surface of the feed tray 38 at the feed end 58 thereof. Since thisflap portion 62 extends substantially perpendicular to the direction oftravel of the dice 16 (i.e., in the direction of arrow 57) at the feedend 58, in the alignment position (FIG. 4A), the flap portion 62 will beplaced in the directly path of the dice. Upon abutting contact with theflap portion, the entire row of dice will be simultaneously stopped, andalign for subsequent die handling.

In the passage position (FIG. 4B), conversely, the flap portion 62 ismoved upwardly and out of the path of the dice, permitting passagethereunder. Such movement between the alignment position and the passageposition will be in a timed manner to cooperate with other componentryof the die separation assembly 30. These include the delivery of theseparated dice 16 onto the collection end 40 of the feed tray 38, andthe delivery of the entire row of aligned dice to the subsequently diehandling devices 63, such as that illustrated in FIG. 3.

Accordingly, in another aspect of the present invention, an altered diehandling device 63 is provided that is similar to that described in theabove-mentioned U.S. Pat. No. 6,364,089. As shown in FIGS. 3–4C, thisdie flipper mechanism 63 includes an elongated, cylindrical-shaped dieflipping wheel 65 rotating about axis 66. The wheel includes a pluralityof rows 67 of die loading stations 68 radially spaced-apart about theperimeter of the wheel at about 45° increments. Each row 67 includes aplurality of die loading stations 68, the number and lateral spacing ofwhich correspond to the number of columns of dice 16 at the feed end 40of the feed tray 38. Thus, when the wheel 65 is positioned in a loadingposition (FIG. 4A), an entire row of dice 16 at the collection tray feedend 40 may be simultaneously loaded into the corresponding loadingstations 68 of the wheel. It also follows that an entire row of dice maybe disposed into the transport cavities 17 of the tape and reel assembly18 at the bottom end thereof.

To facilitate loading of the dice 16 into the loading stations 68 of thewheel 65, the present invention may include a die loading stopper 70,just downstream from the alignment stopper 61. As best viewed in FIG.4A, this loading stopper 70 functions to align die or dice 16 at therespective loading stations 68 on the subsequent die handling device 63for loading thereon. Similar to the alignment stopper 61, the loadingstopper 70 includes a rigid or semi-flexible flap portion 71 extendingvertically downward. This flap portion is adapted for reciprocatingmovement between a mounting position (FIG. 4A) and a retracting position(FIG. 4C). In the mounting position, the distal tip of the flap portion71 is moved into contact, or near contact, with an upper surface of theflipping wheel 65. As the row of dice are urged in the direction ofarrow 57, contact with the flap portion 71 aligns the dice for alignedseating at the respective loading stations 68.

In the retracting position (FIG. 4C), conversely, the flap portion 71 isretracted or moved upwardly and out of the path of the dice. This permitpassage of the mounted dice toward the delivery station into thetransport cavities 17.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

1. A post singulation, die separation assembly configured for separatingadhesive wafer saw tape from the plurality of dice of a singulatedwafer, said assembly comprising: a support base defining a supportsurface and having a first portion and an opposite second portionthereof, said second portion including a down-ramped portion thereofskewed downwardly at a first acute angle from the support surface; afeed tray having a collection end positioned adjacent the base secondportion such that an elongated, substantially thin gap is formed betweenthe tray collection end and at least a portion of the base secondportion; and a flexible platform movably supported atop the base supportsurface for movement from said first portion to said second portionthereof, and downward through the gap formed between the tray collectionend and the at least a portion of the base second portion, said platformdefining an upward facing surface upon which the singulated wafer isadhered thereto, via the saw tape, each die being in a forward alignedmanner; wherein, upon movement of said flexible platform down saiddown-ramped portion, a portion of the wafer saw tape thereat is peeledaway from the respective die, separating and releasing the respectivedie onto the collection end of the feed tray in a manner substantiallymaintaining the forward alignment orientation of each die.
 2. Theseparation assembly as recited in claim 1, wherein said first acuteangle is in the range of about 60° to about 90°.
 3. The separationassembly as recited in claim 2, wherein the base second portion includesan up-ramp portion of the base skewed upwardly at a second acute anglefrom the support surface portion, said up-ramp portion and saiddown-ramp portion intersecting an apex edge portion where said saw tapeis peeled away from the respective die during movement of the adheredwafer thereto.
 4. The separation assembly as recited in claim 3, whereinsaid first acute angle is in the range of about 45° to about 60° andsaid second acute angle is in the range of about 15° to about 30° and,forming an intersection angle of said apex edge portion in the range ofabout 90° to about 120°.
 5. The separation assembly as recited in claim4, wherein said collection end of the feed tray includes a collectionsurface disposed at an elevation proximate that of the apex edgeportion.
 6. The separation assembly as recited in claim 1, wherein thethin gap formed between the tray collection end and the down-rampedportion is less than the height of the separated die and more than thecombined thickness of the flexible platform and the adhered saw tape. 7.The separation assembly as recited in claim 1, further including: a topplate device positioned proximate to said base second portion, andspaced-apart from the base support surface by a distance sufficient tosubstantially prevent flipping of the respective die during separationfrom the saw tape, while maintaining said forward alignment orientationof the die.
 8. The separation assembly as recited in claim 7, whereinthe spaced-apart distance between a bottom surface of said top platedevice and the base support surface is at least less than two times theheight of the die.
 9. The separation assembly as recited in claim 1,further including: a driven roller assembly having a first roller and asecond roller wherein said flexible platform is in the form of anelongated sheet material having one end wound around the first roller,and the opposite end wound around the second roller for said selectivemovement of the flexible platform from the first portion to the secondportion of the base member.
 10. The separation assembly as recited inclaim 9, wherein said elongated sheet material is provided by aone-sided tape material.
 11. The separation assembly as recited in claim1, wherein said flexible platform is provided by a one-sided tapematerial.
 12. A post singulation, bulk feed semiconductor assemblyadapted to separate adhesive wafer saw tape from the plurality of diceof a singulated wafer, and bulk feeding the same in a substantiallyaligned manner, said assembly comprising: a semiconductor feed trayhaving a collection end and an opposite feed end, and a collectionsurface extending from the collection end to the feed end; a dieseparation assembly including: a support base defining a support surfaceand having a first portion and an opposite second portion thereof, saidsecond portion being positioned substantially adjacent the collectionend of the feed tray such that the base support surface is positionedelevationally proximate the tray collection surface, and such that athin elongated gap is formed between the tray collection end and thebase second portion; and a movable platform movably supported atop thebase support surface for movement from said first portion to said secondportion thereof, and downward through the elongated gap formed betweenthe tray collection end and the base second portion at a first acuteangle skewed from the support surface, said platform defining an upwardfacing adherence surface upon which at least one of a plurality ofsingulated wafer is adhered thereto, via the saw tape, each die being ina forward aligned manner, wherein upon movement of said platform throughsaid thin elongated gap, a portion of said wafer saw tape thereat ispeeled away from the respective die or dice, separating and releasingthe respective die or dice onto the collection end of the feed tray in amanner substantially maintaining their respective forward alignmentwhere the dice are urged toward the tray feed end and into contact withthe respective dice previously released onto the collection surface; anda die alignment assembly oriented at the feed end of the feed tray, andadapted to collective cooperate with the dice at the tray feed end forfinal alignment before removal from the feed tray.
 13. The assembly asrecited in claim 12, wherein said die alignment assembly includes afirst die stop extending across and transverse to said feed tray, saiddie stop being selectively movable between a first position, preventingpassage of the dice at the feed end therethrough, and a second position,permitting passage of the dice therethrough.
 14. The assembly as recitedin claim 13, further including: a semiconductor handling devicepositioned proximate the feed end of the feed tray for bulk feed of thealigned dice into discrete stations of the handling device subsequentdie placement thereof.
 15. The assembly as recited in claim 14, furtherincluding: said die alignment assembly includes a second die stopextending across the discrete stations of the handling device, saidsecond die stop being selectively movable between a load position,enabling loading of the dice onto the handling device at the discretestation, and a transport position, permitting transport of the loadeddice on the handling device.
 16. The assembly as recited in claim 12,wherein said second portion includes a down-ramped portion thereofskewed downwardly at said first acute angle from the support surface.17. The assembly as recited in claim 16, wherein the base second portionfurther includes an up-ramp portion of the base skewed upwardly at asecond acute angle from the support surface portion, said up-rampportion and said down-ramp portion intersecting an apex edge portionwhere said saw tape is peeled away from the respective die duringmovement of the adhered wafer thereto.
 18. The assembly as recited inclaim 12, wherein the thin gap formed between the tray collection endand the down-ramped portion is less than the height of the separated dieand more than the combined thickness of the movable platform and theadhered saw tape.
 19. The assembly as recited in claim 12, furtherincluding: a top plate device positioned proximate to said base secondportion, and spaced-apart from the base support surface by a distancesufficient to substantially prevent flipping of the respective dieduring separation from the saw tape, while maintaining.
 20. The assemblyas recited in claim 12, further including: a driven roller assemblyhaving a first roller and a second roller wherein said movable platformis in the form of an elongated sheet material of one-sided adhesive tapematerial having one end wound around the first roller, and the oppositeend wound around the second roller for said selective movement of themovable platform from the first portion to the second portion of thebase member.